For improving a surface of a plastic lens, which has been used for many applications recently, a metal oxide sol having high refractive index is used as a component of hard coating agent applied on the plastic lens surface.
A hard coating agent containing particles of metal oxides such as Al, Ti, Zr, Sn and Sb having a size of 1-300 nm is described. (for example, see Patent Document 1)
Although a stable sol of tungsten oxide alone is not known yet, a sol obtained by adding a silicate in which a molar ratio of WO3:SiO2:M2O (where M represents alkali metal atom or ammonium group) is 4-15:2-5:1 has been proposed (for example, see Patent Document 2).
A silicate-stannate composite sol in which a molar ratio of Si:Sn is 2-1000:1 has been proposed (for example, see Patent Document 3).
A stable sol containing a modified metal oxide colloid having a particle diameter of 4.5-60 nm which is formed by coating colloidal particle surfaces of metal oxide having a particle diameter of 4-50 nm and a valence of 3, 4 or 5 as nuclei with colloidal particles of a tungsten oxide-stannic oxide composite having a mass ratio of WO3/SnO2 of 0.5-100 and a particle diameter of 2-7 nm, and containing 2-50% by mass of total metal oxides has been proposed (for example, see Patent Document 4).
A stable modified SnO2—ZrO2 composite sol containing particles formed by coating colloidal particle spices of SnO2—ZrO2 composite having a mass ratio of ZrO2/SnO2 of 0.02-1.0 and a particle diameter of 4-50 nm as nuclei with colloidal particles of a WO3—SnO2 composite having a mass ratio of WO3/SnO2 of 0.5-100 and a particle diameter of 2-7 nm has been proposed (for example, see Patent Document 5).
A stable modified metal oxide sol containing particles (C) obtained by coating surfaces of colloidal particles of metal oxide (A) having a primary particle diameter of 2-60 nm as nuclei with colloidal particles of acidic oxide (B), and containing 2-50% by mass of (C) calculated as metal oxide and having a primary particle diameter of 2-100 nm is disclosed. A metal oxide as nuclei which is SnO2 particles or SnO2—ZrO2 composite colloidal particles, and a coating material which is Sb2O5 particles containing amine (in which, molar ratio of M/Sb2O5 is 0.02-4.00) have been disclosed (for example, see Patent Document 6).
A production method of a silicic acid-antimonic acid composite solution or a silicic acid-stannic acid composite solution is described in which an alkaline aqueous solution of silicate or a silicate sol dispersion and an alkaline aqueous solution of antimonite or an alkaline aqueous solution of stannate are mixed with a molar ratio of Si:Sb or Si:Sn is 2-1000:1, and then the resultant mixture is decationized by acidic type ion exchanger (for example, see Patent Document 7).
Silicon dioxide-antimony oxide composite sol obtained by dispersing antimony oxide colloidal particles including inorganic silicon oxides of 0.1-50% by mass as SiO2 in a dispersion medium is described (for example, see Patent Document 8).
Plastic molded articles are used widely by utilizing advantages such as lightweight, easy moldability, and high impact resistance. Contrary, plastic molded articles have disadvantages such as being easy to be scratched due to insufficient hardness, being easy to be affected by solvent, absorbing dusts by electrostatic charge and insufficient heat stability. Thus, plastic molded articles have insufficient property for practical use such as glasses lenses and window sashes compared with inorganic glass molded articles. Consequently, applications of protective coating for plastic molded articles are proposed. Much variety of coating composition used for coating is proposed.
“A coating composition using an organic silicon compound or a hydrolysate thereof as a main component (a resin component or a component of a coated film forming)”, which is expected to provide a hard coating film whose hardness is close to an inorganic coating film, is used for glasses lenses (for example, see Patent Document 9).
Since the above-mentioned coating composition still has insufficient scratch resistance, a composition in which a colloidal dispersed silica sol is added to the above-mentioned coating composition has also been proposed, and his composition is put into practical use as glasses lenses (for example, see Patent Document 10).
Meanwhile, conventionally, large part of plastic glasses lenses has been produced by cast polymerization using a monomer called diethylene glycol bis(allyl carbonate). These lenses have a refractive index of approximately 1.50. Since this refractive index is lower than a refractive index of glass lenses of 1.52, plastic lenses have disadvantage of having thicker edge for nearsightedness lenses. Thus, recently, a monomer having higher refractive index than diethylene glycol bis(allyl carbonate) has been developed, and resin materials having high refractive index have been proposed.
With respect to such high refractive index plastic lenses, a method using colloid dispersion of metal oxide fine particles of Sb and Ti as a coating material also has been proposed (for example, see Patent Documents 11 and 12).
In addition, a coating composition containing a stable modified metal oxide sol containing particles (C) obtained by coating surfaces of colloidal particles of metal oxide having a primary particle diameter of 2-60 nm and a silane coupling agent (A) as nuclei with colloidal particles of acidic oxide as a coating material (B), and containing 2-50% by mass of (C) calculated as metal oxides and having a primary particle diameter of 2-100 nm is disclosed. Moreover, a metal oxide as nuclei is SnO2 particles or SnO2—ZrO2 composite colloidal particle, and Sb2O5 particle containing alkyl amine (in which, a molar ratio of M/Sb2O5 is 0.02-4.00) as a coating material is disclosed (for example, see Patent Document 13).
There is disclosed a coating composition containing a modified metal oxide particles obtained by coating surfaces of colloidal particles (A), as nuclei containing a silane coupling agent and stannic oxide particles or stannic oxide-zirconium oxide composite particles having amass ratio of 0:1-0.50:1 based on these oxides and a particle diameter of 4-50 nm with colloidal particles of Sb2O5 containing alkyl amine having a molar ratio of M/Sb2O5 of 0.02-4.00 (where M represents an amine molecule), an oligomer thereof or their mixture (B1), and mass ratio of (B1)/(A) is 0.01-0.50 based on the mass ratio of metal oxides and a particle diameter is 4.560 nm (for example, see Patent Document 14).    Patent Document 1: Japanese Patent Application Publication No. JP-B-63-37142 (Claims)    Patent Document 2: Japanese Patent Application Publication No. JP-A-54-52686 (Claims)    Patent Document 3: Japanese Patent Application Publication No. JP-B-50-40119 (Claims)    Patent Document 4: Japanese Patent Application Publication No. JP-A-3-217230 (Claims)    Patent Document 5: Japanese Patent Application Publication No. JP-A-6-24746 (Claims)    Patent Document 6: Japanese Patent Application Publication No. JP-A-2001-122621 (Claims)    Patent Document 7: Japanese Patent Application Publication No. JP-B-50-40119 (Claims)    Patent Document 8: Japanese Patent Application Publication No. JP-B-7-25549 (Claims)    Patent Document 9: Japanese Patent Application Publication No. JP-A-52-11261 (Claims)    Patent Document 10: Japanese Patent Application Publication No. JP-A-53-111336 (Claims)    Patent Document 11: Japanese Patent Application Publication No. JP-A-62-151801 (Claims)    Patent Document 12: Japanese Patent Application Publication No. JP-A-63-275682 (Claims)    Patent Document 13: Japanese Patent Application Publication No. JP-A-2001-123115 (Claims)    Patent Document 14: Japanese Patent Application Publication No. JP-A-2005-015756 (Claims)